1. Field of the Invention
This application is directed to a catalytic process for hydrotreating heavy hydrocarbon streams containing waxy components, sulfur, metals and asphaltic materials. It more particularly relates to hydroprocessing these heavy hydrocarbon streams using catalytic treatment with a catalyst which effectively provides for demetallation, desulfurization and dewaxing of the hydrocarbon.
2. Description of the Prior Art
It is well known that many, if not most, petroleum base feedstocks contain contaminants, such as, for example, sulfur, nitrogen and metals. It is desirable, particularly if these feedstocks are to be further processed, that the contaminants be removed. This is an operation usually requiring the use of a catalyst. These feedstocks also usually contain waxy components which, because of the resultant high pour point, are difficult to pump and process. Thus, it is also desirable to reduce the amount of waxy component and to accordingly reduce the pour point of the feedstock.
It is known in the art to effect sulfur removal from hydrocarbon stocks by subjecting time to treatment with hydrogen at elevated temperature and pressure while in contact with a catalyst containing hydrogenating components. Typically, the hydrogenating components of such prior art catalysts are Group VIA or Group VIII metals, or their oxides or sulfides. These hydrogenating components may be supported on a variety of wellknown carriers, for example, alumina, kieselguhr, zeolitic molecular sieves and other materials having high surface areas; see in this regard U.S. Pat. No. 4,080,296. U.S. Pat. No. 3,546,103 teaches hydrodesulfurization with a catalyst which includes cobalt and molybdenum on an alumina base. U.S. Pat. No. 3,755,145 describes a process for preparing lube oils, characterized by low pour points, which utilizes a catalyst mixture comprising hydrogenation components, a conventional cracking catalyst which can be either crystalline or amorphous and a crystalline aluminosilicate zeolite having a Constraint Index of 1 to 12.
U.S. Pat. No. 3,894,938 relates to the catalytic dewaxing and desulfurization of high pour point, high sulfur gas oils to lower their sulfur content by contacting such an oil first with a zeolite hydrodewaxing catalyst having a Constraint Index of 1 to 12, which may contain a hydrogenation/dehydrogenation component, in the presence or absence of added hydrogen followed by conventional hydrodesulfurization processing of the dewaxed intermediate.
U.S. Pat. Nos. 4,456,700 and 4,458,024 relate to a process for hydrodewaxing and hydrotreating petroleum residua to more valuable products. The catalyst system described in U.S. Pat. No. 4,458,024 includes a zeolite having a Constraint Index of 1 to 12, an alumina binder, at least one Group VIII metal selected from nickel, cobalt and iron, and at least one Group VIB metal. The catalyst is characterized by specific metals content and pore volume features. A related development is described in copending Application Ser. No. 307,555, filed Oct. 1, 1981.
U.S. Pat. No. 4,225,421 describes a process for hydrodemetallation and hydrodesulfurization of a hydrocarbon feedstock containing asphaltenes and metals by contacting the feedstock with hydrogen and a bimodal catalyst which contains at least one metal, e.g., molybdenum, chromium and tungsten.
U.S. Pat. No. 4,411,770 describes a process for the hydroconversion of heavy hydrocarbon oils, wherein the catalyst comprises a crystalline zeolite component and a metallic hydrogenation component. The zeolites taught as being useful in this process include zeolites having a Constraint Index of 1 to 12 and Na-Beta.
Copending Application Ser. No. 379,421, filed May 18, 1982, discloses a process and catalyst for simultaneously hydrocracking and dewaxing heavy hydrocarbon oils, such as vacuum gas oil. The catalyst system utilized is described as including 10-99% by weight, preferably 25-80% by weight Zeolite Beta, a porous matrix material, such as alumina, and a hydrogenation component derived from one or more metals of Groups VA, VIA or VIIIA of the Periodic Table (the Periodic Table referred to herein is the Table approved by IUPAC and the U.S. National Bureau of Standards, and is shown, for example, in the Table of the Fisher Scientific Company, Catalog No. 5-702-10, and is the Table of reference for this application).
Copending Application Ser. No. 310,550, filed Oct. 13, 1981, now abandoned, describes a single stage operation for hydrotreating and hydrodewaxing of petroleum residua using a dual catalyst system, i.e., a hydrodesulfurization catalyst combined with a metal-containing ZSM-5 hydrodewaxing catalyst.
Copending application Ser. No. 665,605, filed Oct. 29, 1984, describes a process for simultaneously hydrotreating and dewaxing distillable petroleum fractions using a catalyst comprising Zeolite Beta, an inorganic oxide material and a hydrogenation/dehydrogenation component.